Emergency telephone communications system

• US 5,844,974 A
• Filed: 05/21/1996
• Issued: 12/01/1998
• Est. Priority Date: 05/22/1995
• Status: Expired due to Fees

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Ichikawa, Yasuyo
• Primary Examiner(s): Loomis, Paul
• Application Number:
  US08/651,850
• Time in Patent Office: 924 Days
• Field of Search: 379/67, 379/88, 379/89, 379/112, 379/113, 379/132, 379/133, 379/134, 379/135, 379/137, 379/138, 379/201, 379/207, 379/219, 379/220, 379/221, 379/265, 379/266, 379/45, 379/37 , 379/46, 379/47, 379/48, 379/67.1, 379/88.01, 379/69
• US Class Current: 379/138
• CPC Class Codes: H04M 3/36 Statistical metering, e.g. recording occasions when traffic exceeds capacity of trunks
• CPC Class Codes: H04M 3/487 Arrangements for providing information services, e.g. recorded voice services or time announcements

Abstract

An emergency telephone communications system allows communications during congestion in the event of disaster. The system includes an exchange and telephones connected to the line circuits thereof. The exchange sends a congestion generation signal to a control section to initiate emergency processing when a congestion detecting circuit detects more than a predetermined number of the line circuits in the off-hook state. The control section has a congestion management table listing subscribers and stores not-yet-serviced subscribers when congestion has occurred. The not-yet-serviced subscribers are successively selected from the congestion management table, and calling signals are sent to their telephones. When the subscribers go off-hook within a predetermined time, the control section controls the emergency dial pulse receiver circuit to be ready for reception, and then controls the switch to connect an emergency service trunk to the line circuits to send a tone signal or a voice message. Upon receipt of telephone numbers of the receiving parties sent from the subscribers, the exchanges at the receiving parties are called through the emergency trunk circuit. The telephones send telephone numbers of the receiving parties at a predetermined time after detection of incoming calls from the exchange, or after detection of a given signal.

Claims

1. An emergency telephone communications system for communicating a telephone signal during congestion of an exchange, comprising:

an exchange having control means for allocating one or more trunk lines and common control circuits as emergency trunk line resources between exchanges;

means for selecting and connecting subscriber lines in a predetermined order through the allocated common control circuits to send calling signals;

means for detecting answers to the calling signals;

means for inputting receiving party-designating signals designated by subscribers; and

means for conducting processing for connection with receiving parties based on said receiving party-designating signals through said emergency trunk lines; and

telephones having means for detecting incoming calls from said exchange;

means for sending receiving party-designating signals at a predetermined time after detection of the calls in or after receipt of a predetermined signal; and

means for sending prerecorded messages.

2. An emergency telephone communications system as claimed in claim 1, wherein said control means allocates a predetermined number of trunk lines and common control circuits as said emergency line resources when a predetermined number of said common control circuits are detected to be used over a predetermined time.

3. An exchange for use in an emergency telephone communications system, comprising:

control means for allocating one or more trunk lines and common control circuits as emergency trunk lines resources between exchanges;

means for selecting and connecting subscriber lines in a predetermined order through the allocated common control circuits to send calling signals;

means for detecting answers to the calling signals;

means for receiving party-designating signals designated by subscribers; and

means for conducting processing for connection with receiving parties based on said receiving party-designating signals through said emergency trunk lines.

4. An exchange as claimed in claim 3, wherein said control means allocates a predetermined number of trunk lines and common control circuits as said emergency line resources when a predetermined number of said common control circuits are detected to be used over a predetermined time.

5. A telephone exchange which has line circuits connected to subscriber lines, trunk lines and switches, and serves to connect the lines, further comprising:

a circuit for detecting congestion of line circuits;

a congestion management table for the subscribers;

an emergency service trunk circuit;

recording means for recording information in the congestion management table which identifies at least the subscribers other than those engaging in conversation when the congestion of the line circuits is detected; and

control means for securing an emergency trunk line and common control circuits, and serving to call up the not-yet-serviced subscribers in succession through the emergency service trunk circuit and the common control circuits based on the congestion management table, to connect answering, not-yet-serviced subscribers to designated receiving subscribers through the emergency trunk line.

6. A telephone exchange as claimed in claim 5, wherein said control means secures at least one open trunk line and common control circuit in the order of call termination after detection of the congestion.

7. A telephone exchange as claimed in claim 6, which sends a predetermined message to the subscriber engaging in conversation and then forcibly interrupts the conversation if the conversation continues over a predetermined time.